LTC2408CG Linear Technology, LTC2408CG Datasheet - Page 33

• Manufacturer Part Number: LTC2408CG
• Description: IC A/D CONV 24BIT 8-CHAN 28-SSOP
• Manufacturer: Linear Technology

Specifications of LTC2408CG

• Number Of Bits: 24
• Sampling Rate (per Second): 7.5
• Data Interface: MICROWIRE™, Serial, SPI™
• Number Of Converters: 1
• Power Dissipation (max): 1mW
• Voltage Supply Source: Single Supply
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 28-SSOP (0.200", 5.30mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIONS
ENLWMX TBA
MUXSPI
*
WAITMUX LDAA
*
***************************************
* Enable the LTC2408
***************************************
*
*
*
***************************************
* The next short loop waits for the
* LTC2408’s conversion to finish before
* starting the SPI data transfer
***************************************
*
CONVEND LDAA
*
*
*
*
*
***************************************
* The SPI data transfer
***************************************
*
TRFLP1
*
WAIT1
*
*
*
*
*
*
An 8-Channel DC-to-Daylight Digitizer
The circuit in Figure 31 shows an example of the LTC2408’s
flexibility in digitizing a number of real-world physical
phenomena—from DC voltages to ultraviolet light. All of
the examples implement single-ended signal condition-
ing. Although differential signal conditioning is a preferred
approach in applications where the sensor is a bridge-
ORAA
STAA
BCLR
ANDA
BNE
LDAA
STAA
LDAA
BPL
LDAA
STAA
INX
CPX
BNE
BSET
PULA
PULY
PULX
RTS
#$08
SPDR
SPSR
BPL
PORTD,Y %00100000 This sets the SS* output bit to a logic
PORTD
#%00000100
CONVEND
#$0
SPDR
SPSR
SPDR
0,X
PORTD,Y %00100000 This sets the SS* output bit to a logic
U
Restore contents of Accum. A
Set the MUX’s ENABLE bit
Transfer Accum. A contents to SPI register to initiate
serial transfer
Get SPI transfer status
WAITMUX If the transfer is not finished, read status
Load accumulator A with a null byte for SPI transfer
This writes the byte into the SPI data register and
starts the transfer
This loop waits for the SPI to complete a serial
transfer/exchange by reading the SPI Status Register
WAIT1 The SPIF (SPI transfer complete flag) bit is the SPSR’s
MSB and is set to one at the end of an SPI transfer. The
branch will occur while SPIF is a zero.
Load accumulator A with the current byte of LTC2408 data
that was just received
Transfer the LTC2408’s data to memory
Increment the pointer
#DIN4+1 Has the last byte been transferred/exchanged?
TRFLP1 If the last byte has not been reached, then proceed to
the next byte for transfer/exchage
Restore the A register
Restore the Y register
Restore the X register
INFORMATION
U
Figure 30. LTC2408/LTC1391-684C11 MCU Digital Interface Routine
*
*
*
*
Retrieve the contents of port D
Look at bit 2
Bit 2 = Hi; the LTC2408’s conversion is not
complete
Bit 2 = Lo; the LTC2408’s conversion is complete
Branch to the loop’s beginning while bit 2 remains
high
*
high, de-selecting the LTC2408
W
low, selecting the LTC2408
U
type, is located some distance from the ADC or operates
in a high ambient noise environment, the LTC2408’s low
power dissipation allows circuit operation in close prox-
imity to the sensor. As a result, conditioning the sensor
output can be greatly simplified through the use of single-
ended arrangements. In those applications where differ-
ential signal conditioning is required, chopper
LTC2404/LTC2408
33